In polycarbonate/acrylonitrile butadiene styrene (PC/ABS) compositions including PC and ABS copolymers, PC generally improves impact strength and heat resistance, and ABS enhances processability and chemical resistance. As such, PC/ABS compositions can be used for various purposes due to their excellent physical properties as compared with ABS and cost efficiency as compared with PC.
For example, PC/ABS compositions may be used in the production of housings for electronic products. Generally such products require flame retardancy. Adding 10 wt % triphenyl phosphate (TPP) to a PC/ABS composition can impart about V0-level flame retardancy. In this case, however, evaporation may occur during a bridging or extrusion process due to the low melting point of TPP.
Thus, bromide, phosphate ester, and sulfonate flame retardants may be considered. Phosphate ester flame retardants, which are non-halogenated flame retardants, are environmentally friendly as compared with bromide flame retardants. Phosphate ester flame retardants, however, generally must be added in an amount of 10 wt % or more to provide a UL94 flammability rating of about V0 or more.
Phosphorus flame retardants including resorcinol bis(diphenyl phosphate) (RDP) or bisphenol A bis(diphenyl phosphate) (BDP) may also be used. Compositions including these flame retardants can be injection molded at 250° C. because RDP and BDP increase the flow index. However, the use of RDP or BDP as flame retardants is regulated due to recent environmental restrictions.
Sulfonate flame retardants can provide excellent flame retardancy even in an amount as low as 1 wt % or less and also provide advantages associated with non-halogenated flame retardants. However, when sulfonate flame retardants are used for a composition including PC and ABS copolymers, a high injection molding temperature of 280° C. or more is generally required. When the injection, molding temperature becomes high, impact strength and heat resistance can be deteriorated due to decomposition of resin or the like.
Thus, there is a need for a polycarbonate resin that has enhanced fluidity and improved impact strength, and is capable of maintaining gloss and flame retardancy.